The present invention relates generally to a chuck apparatus and method for gripping a tool or workpiece and more particularly to an automatic rotating hydraulic chuck construction and method using a number of jaws moved radially inward and outward for gripping a drill pipe for earth boring machines.
A chuck for gripping a drill pipe in an earth boring machine should provide a high gripping force for securely gripping the drill pipe, and additionally should provide substantial movement of the gripping surfaces for releasing the drill pipe. In use, chucks may become clogged with material removed from the workpiece. In the case of earth boring machines, the chuck may become clogged with dirt, clay or other earth material, which may cake and harden and which may adversely affect the operation of the chuck. In earth boring machines, because of the accumulation of earth material on the drill rods, normal movement of the jaws does not provide adequate clearance for smooth passage of the drill rods through the chuck.
In one known construction, as shown in Buck, U.S. Pat. No. 3,731,942, the chuck includes a gripping sleeve positioned in a housing. The gripping sleeve and the housing are each provided with a number of cam surfaces. When the sleeve is moved relative to the housing the sleeve is deformed radially inward to engage and grip the drill rod.
In other known devices, jaws are moved radially inward by the movement of a bowl or wedge. The rear surfaces of the jaws bear against the wedge or bowl on a single plane having a steep angle for effecting a high gripping force on the drill rod. Examples of such devices include Janson, U.S. Pat. No. 2,768,830, Siebelhoff, U.S. Pat. No. 3,427,036, Braun, U.S. Pat. No. 3,792,869, Crawshay, U.S. Pat. No. 3,992,019, Kutman et al, U.S. Pat. No. 4,196,914, Lambot, U.S. Pat. No. 4,273,200, Acker, U.S. Pat. No. 3,076,245 and Acker, Jr., U.S. Pat. No. 2,905,998. These devices provide relatively little movement of the jaws for releasing the drill rod.
There is a need in the art for a chuck construction which provides a high gripping force to grip the drill rod and greater horizontal movement of the gripping surface for releasing the rod.